White-opaque switching in Candida albicans.

The human commensal yeast Candida albicans undergoes an epigenetic switch between two distinct types of cells, referred to as white and opaque. These two cell types differ in many respects, including their cell and colony morphologies, their metabolic states, their mating behaviors, their preferred niches in the host, and their interactions with the host immune system. Each of the two cell types is heritable for many generations and switching between them appears stochastic; however, environmental cues can significantly alter the frequency of switching. We review recent work on white-opaque switching, including the establishment of the transcriptional circuit underlying this switch, the identification of environmental signals that affect switching rates, newly discovered differences between the two types of cells, and the involvement of white-opaque switching in biofilm formation. We also review recent speculation on the evolution and adaptive value of white-opaque switching.